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Thursday, 16 January 2014

Afinitor (everolimus)

Everolimus is a derivative of Rapamycin (sirolimus), and works similarly to Rapamycin as an mTOR (mammalian target of rapamycin) inhibitor. It is currently used as an immunosuppressant to prevent rejection of organ transplants. In a similar fashion to other mTOR inhibitors Everolimus' effect is solely on the mTORC1 protein and not on the mTORC2 protein.

Afinitor (everolimus), an inhibitor of mTOR (mammalian target of rapamycin), is an antineoplastic agent.

Afinitor is specifically approved for the treatment of postmenopausal women with advanced hormone receptor-positive, HER2-negative breast cancer (advanced HR+ BC) in combination with exemestane, after failure of treatment with letrozole or anastrozole.

Afinitor is supplied as a tablet for oral administration. The recommended dose of Afinitor for breast cancer is 10 mg, to be taken once daily, at the same time every day, either consistently with food or consistently without food.

FDA ApprovalThe FDA approval of Afinitor for the treatment of advanced hormone receptor-positive, HER2-negative breast cancer was based on a randomized, double-blind, multicenter study in 724 postmenopausal women with estrogen receptor-positive, HER 2/neu-negative advanced breast cancer with recurrence or progression following prior therapy with letrozole or anastrozole.

Everolimus is indicated for the treatment of postmenopausal women with advanced hormone receptor-positive, HER2-negative breast cancer (advanced HR+ BC) in combination with exemestane, after failure of treatment with letrozole or anastrozole. Indicated for the treatment of adult patients with progressive neuroendocrine tumors of pancreatic origin (PNET) with unresectable, locally advanced or metastatic disease. Indicated for the treatment of adult patients with advanced renal cell carcinoma (RCC) after failure of treatment with sunitinib or sorafenib. Indicated for the treatment of adult patients with renal angiomyolipoma and tuberous sclerosis complex (TSC), not requiring immediate surgery. Indicated in pediatric and adult patients with tuberous sclerosis complex (TSC) for the treatment of subependymal giant cell astrocytoma (SEGA) that requires therapeutic intervention but cannot be curatively resected.

Everolimus(RAD-001) is the 40-O-(2-hydroxyethyl) derivative of sirolimus and works similarly to sirolimus as an inhibitor of mammalian target of rapamycin (mTOR).

It is currently used as an immunosuppressant to prevent rejection of organ transplants and treatment of renal cell cancer and other tumours. Much research has also been conducted on everolimus and other mTOR inhibitors for use in a number of cancers.

It is marketed by Novartis under the tradenamesZortress(USA) andCertican(Europe and other countries) in transplantation medicine, andAfinitorin oncology.

EVEROLIMUS

AFINITOR (everolimus), an inhibitor of mTOR, is an antineoplastic agent.

The chemical name of everolimus is (1R,9S,12S,15R,16E,18R,19R,21R,23S,24E,26E,28E,30S,32S,35R)-1,18- dihydroxy-12-{(1R)-2-[(1S,3R,4R)-4-(2-hydroxyethoxy)-3-methoxycyclohexyl]-1-methylethyl}-19,30-dimethoxy15,17,21,23,29,35-hexamethyl-11,36-dioxa-4-aza-tricyclo[30.3.1.04,9]hexatriaconta-16,24,26,28-tetraene-2,3,10,14,20pentaone.

The molecular formula is C53H83NO14 and the molecular weight is 958.2. The structural formula is:

Rapamycin is a known macrolide antibiotic produced by Streptomvces hvgroscopicus. having the structure depicted in Formula A:

See, e.g., McAlpine, J.B., et al., J. Antibiotics (1991) 44: 688; Schreiber, S.L., et al., J. Am. Chem. Soc. (1991) J_13: 7433'- US Patent No. 3 929 992. Rapamycin is an extremely potent immunosuppressant and has also been shown to have antitumor and antifungal activity. Its utility as a pharmaceutical, however, is restricted by its very low and variable bioavailabiiity as well as its high toxicity. Moreover, rapamycin is highly insoluble, making it difficult to formulate stable galenic compositions.

Everolimus, 40-O-(2-hydroxyethyl)-rapamycin of formula (1) is a synthetic derivative of rapamycin (sirolimus) of formula (2), which is produced by a certain bacteria strain and is also pharmaceutically active.

(1) (2)

Everolimus is marketed under the brand name Certican for the prevention of rejection episodes following heart and kidney transplantation, and under the brand name Afinitor for treatment of advanced kidney cancer.

Due to its complicated macrolide chemical structure, everolimus is, similarly as the parent rapamycin, an extremely unstable compound. It is sensitive, in particular, towards oxidation, including aerial oxidation. It is also unstable at temperatures higher than 25°C and at alkaline pH.

Everolimus and a process of making it have been disclosed in WO 94/09010

(US 5,665,772, EP 663916). The process principle is shown in the scheme below, wherein the abbreviation RAP-OH has been used as an abbreviation for the rapamycin structure of formula (2) above, L is a leaving group and P is a trisubstituted silyl group serving as a OH- protective group.

RAP-OH + L-CH2-CH2-0-P — --> RAP-O-CH2-CH2-O-P — - > RAP-O-CH2-CH2-OH

(2) (4) (1)

Specifically, the L- group is a trifluoromethanesulfonate (triflate) group and the protective group P- is typically a tert-butyldimethylsilyloxy- group. Accordingly, the known useful reagent within the above general formula (3) for making everolimus from rapamycin is 2-(tert-butyldimethylsilyloxy)ethyl triflate of formula (3 A):

According to a known synthetic procedure disclosed in Example 8 of WO 94/09010 and in Example 1 of US application 2003/0125800, rapamycin (2) reacts in hot toluene and in the presence of 2,6-lutidine with a molar excess of the compound (3 A), which is charged in several portions, to form the t-butyldimethylsilyl-protected everolimus (4A). This compound is isolated and deprotected by means of IN aqueous HC1 in methanol. Crude everolimus is then purified by column chromatography. Yields were not reported.

(2) (3A) (4A) (1)

In an article of Moenius et al. (J. Labelled Cpd. Radiopharm. 43, 113-120 (2000)), which used the above process for making C14-labelled and tritiated everolimus, a diphenyl- tert.butylsilyloxy -protective group was used as the alkylation agent of formula (3B).

Only 8% yield of the corresponding compound (4B)

and 21% yield of the compound (1) have been reported.

Little is known about the compounds of the general formula (3) and methods of their preparation. The synthesis of the compound (3 A) was disclosed in Example 1 of US application 2003/0125800. It should be noted that specification of the reaction solvent in the key step B of this synthesis was omitted in the disclosure; however, the data about isolation of the product allow for estimation that such solvent is dichloromethane. Similarly also a second article of Moenius et al. (J. Labelled Cpd. Radiopharm.42, 29-41 (1999)) teaches that dichloromethane is the solvent in the reaction.

It appears that the compounds of formula (3) are very reactive, and thus also very unstable compounds. This is reflected by the fact that the yields of the reaction with rapamycine are very low and the compound (3) is charged in high molar extent. Methods how to monitor the reactivity and/or improve the stability of compounds of general formula (3), however, do not exist.

Thus, it would be useful to improve both processes of making compounds of formula (3) and, as well, processes of their application in chemical synthesis.

In a 100 mL flask, Rapamycin (6 g, 6.56 mmol) was dissolved in dimethoxyethane (4.2 ml) and toluene (24 ml) to give a white suspension and the temperature was raised to 70°C. After 20 min, N,N-diisopropylethylamine (4.56 ml, 27.6 mmol) and 2-((2,3-dimethylbutan-2- yl)dimethylsilyloxy)ethyl trifluoromethanesulfonate (8.83 g, 26.3 mmol) were added in 2 portions with a 2 hr interval at 70°C. The mixture was stirred overnight at room temperature, then diluted with EtOAc (40 ml) and washed with sat. NaHC03 (30 ml) and brine (30 ml). The organic layer was dried with Na2S04, filtered and concentrated. The cmde product was chromatographed on a silica gel column (EtOAc/heptane 1/1 ; yield 4.47 g).

Example 7: 40-O-(2-hydroxyethyl)-rapamycin [everolimus]

In a 100 mL flask, 40-O-[2-((2,3-dimethylbut-2-yl)dimethylsilyloxy)ethyl]rapamycin (4.47 g, 4.06 mmol) was dissolved in methanol (20 ml) to give a colorless solution. At 0°C, IN aqueous hydrochloric acid (2.0 ml, 2.0 mmol) was added and the mixture was stirred for 90 min. The reaction was followed by TLC (ethyl acetate/n-heptane 3 :2) and HPLC. Then 20 ml of saturated aqueous NaHC03 were added, followed by 20 ml of brine and 80 ml of ethyl acetate. The phases were separated and the organic layer was washed with saturated aqueous NaCl until pH 6/7. The organic layer was dried by Na2S04, filtered and concentrated to yield 3.3 g of the product.

A solution of 9.14 g (10 mmol) of rapamycin and 4.70 mL (40 mmol) of 2,6-lutidine in 30 mL of toluene is warmed to 60°C and a solution of 6.17 g (20 mmol) of 2-(t-butyldimethylsilyl)oxyethyl triflate and 2.35 mL (20 mmol) of 2,6-lutidine in 20 mL of toluene is added. This mixture is stirred for 1.5h. Then two batches of a solution of 3.08 g (10 mmol) of triflate and 1.2 mL (10 mmol) of 2,6-lutidine in 10 mL of toluene are added in a 1.5h interval. After addition of the last batch, stirring is continued at 60°C for 2h and the resulting brown suspension is filtered. The filtrate is diluted with ethyl acetate and washed with aq. sodium bicarbonate and brine. The organic solution is dried over anhydrous sodium sulfate, filtered and concentrated. The residue is purified by column chromatography on silica gel (40:60 hexane-ethyl acetate) to afford 40-O-[2-(t-butyldimethylsilyl)oxy]ethyl-rapamycin as a white solid: 1H NMR (CDCl3) δ 0.06 (6H, s), 0.72 (1H, dd), 0.90 (9H, s), 1.65 (3H, s), 1.75 (3H, s), 3.02 (1H, m), 3.63 (3H, m), 3.72 (3H, m); MS (FAB) m/z 1094 ([M+Na]+), 1022 ([M-(OCH3+H2O)]+).

b) 40-O-(2-Hydroxy)ethyl-rapamycin

To a stirred, cooled (0°C) solution of 4.5 g (4.2 mmol) of 40-O-[2-(t-butyldimethylsilyl)oxy]ethyl-rapamycin in 20 mL of methanol is added 2 mL of IN HCl. This solution is stirred for 2h and neutralized with aq. sodium bicarbonate. The mixture is extracted with three portions of ethyl acetate. The organic solution is washed with aq.

Everolimus (Everolimus) was synthesized by the Sirolimus (sirolimus, also known as rapamycin Rapamycin) ether from. Sirolimus is from the soil bacterium Streptomyces hygroscopicus isolated metabolites. Activation end sirolimus (triflate, Tf) the other end of the protection (t-butyldimethylsilyl, TBS) of ethylene glycol 1 reaction of 2 , because the hydroxyl group 42 hydroxyl site over the 31-bit resistance is small, so the reaction only occurs in 42. Compound 2under acidic conditions TBS protection is removed everolimus.

MYSELF

DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK PHARMACEUTICALS LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India.

Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him worlddrugtracker.

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OLD BIO

DR ANTHONY MELVIN CRASTO Ph.D , Born in Mumbai in 1964 and graduated from Mumbai University, Completed his PhD from ICT ,1991, Mumbai, India in Organic chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues,

Currently he is working with GLENMARKPHARMA LTD, Research centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India.

Prior to joining Glenmark, he worked with major multinationals like Hoechst Marion Roussel, now Sanofi Aventis, & Searle India ltd, now RPG lifesciences, etc. He has worked in Basic research, Neutraceuticals, Natural products, Flavors, Fragrances, Pheromones, Vet Drugs, Drugs, formulation, GMP etc. He has total 29 yrs exp in this field, he is now helping millions, has million hits on google on all organic chemistry websites.

He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 25 year tenure, good knowledge of IPM, GMP, Regulatory aspects, he has several international drug patents published worldwide .

He suffered a paralytic stroke in dec 2007 and is bound to a wheelchair, this seems to have injected feul in him to help chemists around the world, he is more active than before and is pushing boundaries, he has one lakh connections on all networking sites, He makes himself available to all, contact him on +91 9323115463, amcrasto@gmail.com, Twitter @amcrasto